Zooker,
We will not be 50+ controllers short. Probably half that.
Interestingly when the VR was announced a couple of years ago the (now) CEO attended a watch meeting. I asked him (and this is the best recollection of the question) "Given NATS' previous inability to predict required staff numbers, are you happy that the amount of people being released on VR is sensible? Then went on to explain that I started at NATS we had shiftwork in the college, my course had about 60 people as we were so short of controllers and someone panicked. No one thought that if the same ration of people passed out of the college then there would not be enough resource to train them at the units. 3 months later half the course was held over!
In his answer Mr Rolfe acknowledged past mistakes but assured us that the number crunching was correct.
So now we are short of people and traffic is going to grow at a greater rate over the next few years.
The next train crash will be when the current crop of controllers in their mid forties retire... there is a huge number in that age bracket...